I know that the 235 is the size of the original motor, but believe the engine currently in the car may be a replacement engine that my father put in. However, I've been told that he kept the original motor and was intending to rebuild it and put it back into the car. Dad passed away several years ago, and I'm trying to find that motor amongst all the old motors which are setting around his shop. Being female, I don't know all there is to know about how to identify the motors! Therefore, I need help!
Thanks...

There are hundreds of online sites that have engine identification or casting number decoding information.
Just google something like "chevy 6 cylinder identification"
At least you can find a number that was used in 55 Chevys and
you can verify an engine manufactured prior to the car manufacturing date.
Also look up "verify numbers matching" for reference material.